Centerless grinding machine for tapered work pieces



E. F. RENDER Aug. 30, 1960 CENTERLESS GRINDING MACHINE FOR TAPERBD WORK PIECES Filed April 21, 1958 2 Sheets-Sheet 1 5 m w 5 o E 5 MW M C a M M T m 5 E 1 T w F M M A O I u 1 l m /7 I y 5 7 M U/fv6 3 ll 4 9 i 6 0 5 G I a 7 V 5 5 a g a a Z 5. H4 2 3 5 3 \l 5 0 6 6 3 H z ..u H/ 7 4 6. B 1 2 A N D b a 9 b a H z 0 6 2 a 6 2 4 9 l i. 5 2 6 W22 7 2 5 a: 2 2 m 5 Aug. 30, 1960 E. F. RENDER 2,959,580

CENTERLESS GRINDING MACHINE FOR TAPEIRED WORK PIECES Filed April 21, 1958 2 Shets-Sheet 2 INVENTOR. ELIJAH F. RENDER ATTORNEYS hired States Patent new Patented Aug. 33, 398C? Fire CENTEP$ESS GRINDBNG MACHHNE FOR TAPERED WORK PIECES Elijah F. Render, Madeira, Ohio, assignor to The Cincinnati Milling Machine Co., Cincinnati, Ohio, a corporation of Ohio Filed Apr. 21, 1958, Ser. No. 729,952

4 Claims. ((11. 51-403) This invention relates to centerless grinding machines and more particularly to a new and improved construction more particularly adapted for grinding tapered work.

in the art of centerless grinding it is well known that work may be ground by either the infeed method, or the through feed method. In the infeed method, the work does not move axially while the regulating Wheel is bodily moved or fed toward the work by a suitable infeed mechanism to effect the grinding operation. In the through feed method, the regulating wheel is not fed but dressed in a particular manner to automatically provide an axial feed component to the work simultaneously with imparting rotation thereto, whereby the work is continually fed through the machine while the regulating wheel is held in a fixed position. It has been found that neither of these methods is entirely satisfactory for grinding small tapered workpieces at a high rate of production. It is, therefore, proposed in this invention to provide a new and improved method of centerless grinding tapered work which utilizes part of the infeed method and part of the through feed method to provide a highly productive and accurate machine.

One of the objects of this invention is to provide an improved automatic centerless grinding machine for gn'nding relatively short tapered workat a high production rate and with relatively high precision.

Another object of this invention is to provide a new and improved centerless grinder having a solid notched type regulating wheel for grinding tapered work, the regulating wheel having one or more work ejecting notches formed in its periphery, together with suitable work feeding mecham sm suitably so coordinated that a complete grinding operation is performed on a single workpiece during rotation of the regulating wheel through an angle equal to the angle between the notches.

A further object of this invention is to provide a new and improved centerless grinder with a conical shaped grinding throat into the large end of which the tapered work is fed or pushed so that the backward or retrograde force reactions created thereby on the work will react to maintain the work in contact with the pushing means, thus eliminating the necessity for a positive stop for sizing purposes.

in the illustrated embodiment of the invention herein, the tapered grinding throat is formed by providing opposed conical shaped wheels and an intermediate work rest blade all having an angle of taper about a horizontal axis equal to the desired angle of taper to be formed on the work.

Still another object of this invention is to provide an improved centerless grinder of the character described in which the pushing means is timed with the rotation of the regulating wheel so that the feeding movement imparted to the work is completed in the time that it tfies the regulating wheel to rotate through its working angle between notches.

In the present embodiment the pushing means is at- 2 tached to the regulating wheel and is in the form of cam means engageable with the large end of a tapered workpiece for imparting feeding motion thereto into a tapered or conical grinding throat and so contrived as to automatically determine the size of the work.

Qther objects and advantages of the present invention should be readily apparent by reference to the following specification, considered in conjunction with the accompanying drawings forming a part thereof, and it is to be understood that any modifications may be made in the exact structural details there shown and described, within the scope of the appended claims, without departing from or exceeding the spirit of the invention.

Referring to the drawings, in which like reference numerals indicate like or similar parts:

Fig. 1 is an elevational view of a centerless grinding machine constructed in conformity to the present invention;

Fig. 2 is an enlarged elevational fragmentary view, partly in cross-section, of the grinding and regulating wheels of the machine of Fig. 1;

Fig. 3 is a view through section 33 ofFig. 2 showing a developmental view of the cam;

Fig. 4 is a view through section 4-4 of Fig. 2 showing the position of the workpiece when the forward end of the cam is opposite the blade position;

Fig. 5 is a View similar to Fig. 4 except that the regulating wheel has rotated from its position in Fig. 4 to a position where the rear end of the cam is opposite the blade position;

Fig. 6 is a fragmentary elevational view of the grinding and regulating wheels and the throat therebetween when the notch is opposite the blade position and showing the workpiece immediately before and immediately after it drops off the blade into the notch; and

Fig. 7 is a view through section 77 of Fig. 6.

A centerless grinding machine constructed in accordmce with the present invention is shown in Fig. 1. The machine has a base 11, an upstanding control cabinet 12, an upstanding wheel head 13, and an upstanding base portion 25. A fixed spindle 14 is rigidly but rotatably mounted on the wheel head 13 and defines a central axis A of rotation for the grinding Wheel 15 mounted thereon. The grinding wheel 15 is secured to the spindle 14 by nut 16 and is partially enclosed by a cover 17. The grinding wheel spindle is driven by a motor (not shown) housed in the motor cabinet 18. The truing mechanism for the grinding wheel, shown generally at 20, is mounted on a slide 21 which is mounted to swivel on the upstanding base portion 25. The slide 21 has cross ways 22 which slidably receive the body 23 of the truing mechanism. A sleeve 24 is slidably received in the body 23, and is urged inwardly in relation thereto and threadedly receives the diamond tipped truing bar 25, which engages the grinding wheel for truing, the axial movement of the truing bar being controlled by crank 26. A cam 27 on the slide 21 engages follower 28 on the sleeve 24 to control axial movement of the sleeve, and hence the truing bar, as the body 23 moves across the slide 21 on the ways 22. The cross movement of the body 23 is controlled by the engaging lever 29a and the rate adjustment control 2%.

The regulating wheel 39 is mounted on spindle 31 which defines a central axis B of rotation therefor. The regulating wheel is secured to the spindle 31 by nut 32. The spindle 31 is mounted in the regulating wheel housing 42 which, in turn, is mounted on the upper slide 33 which contains the motor (not shown) for driving the regulating Wheel. The slide 33 is mounted on the ways 35 of the lower slide 41 for movement of the housing towards or away from the grinding wheel. The slide 4-1 is mounted on the ways 34 of the base 11 and also moves in and away from the grinding wheel, supporting at its inboard end the upstanding blade holder 61a in which is supported the work rest blade 61.

The movement of the slide 41 in relation to the base 11 serves to position the work rest blade 61and the regulating wheel at the proper distance from the grinding wheel to accommodate a particular sized'workpiece while the individual movement of the slide 33 in relation to the slide 41 serves to move the regulating Wheel with respect to the work rest blade 61. The sole movement of the upper slide 33 in relation to the lower slide 41, and the joint movement of the slides 41 and 33 in relation to the basell is controlled by the infeedhand wheel 37. The regulating wheel angular velocity is indicated by the tachometer 'dial 38.

As shown in Figs. 2, 4, 5, 6, and 7, the grinding wheel 15 has a side face 50, with periphery 50a, and an opposite side face 51 with periphery 51a. The peripheral face 52 of the grinding wheel 15 defines a cutting surface which is beveled, the periphery 50a of the side face 50 being smaller than the periphery 51a of the side face 51.

The regulating wheel 30 has a side face 55, the outer margin 550 of which is recessed. The side face 55 has a periphery 55a. The'regulatingwheel 30 also has an opposite side face 56 with'a periphery 56a and a peripheral face 57 which defines a work engaging surface. The face 57 is beveled at an angle equal to the bevel of the face 52 of the grinding wheel. 15, the periphery '55:; of the side face 55 of the regulating wheel being smaller than the periphery 56a of the side face 56.

The regulating wheel 30 is located adjacent the grinding wheel 15 and in spaced relation thereto. The central axis B of the regulating wheel 30 is parallel to and fixed in relation to axis A of the grinding wheel 15 during the grinding operation. The face 57 of the regulating wheel 30 is opposite the face 52 of the grinding wheel 15 and spaced therefrom to define a symmetrically tapered throat 60 therebetween, the throat having a larger end 60a and a narrower end 60b, the latter at the sidefaces 51'and 56 of the wheels. The throat 60 has a longitudinal axis C parallel to the axes A and B of the grinding wheel15 and regulating wheel 30 respectively. Because the axes of the grinding wheel and regulating wheels are centered and are fixed in relation to each other during the grinding operation, the size of the tapered throat is constant while the workpiece-is being ground.

A Work supporting blade 61 is mounted on the blade holder 61a and extends up into the throat 60. and is provided with a sloping work supporting face 62 dropping in the direction of the regulating wheel 30. A tapered workpiece 65, having a larger end at 6511 and a smaller end 65b, which may, for example, be a roller for a roller hearing, has a longitudinal axis D, as shown in Fig. 7. The workpiece 65 is received in the throat, with its central axis D coincident to axis C of the'throat, shown in Fig. 4, andseats on the sloping face 62 of the blade 61.

The grinding wheel, the regulating wheel and the work rest form the grinding throat of the machine, but the parts are so formed that it is a tapered grinding throat, having a large end and a small end. It will be noticed from Figures 4 and that the rims 51a and 56a, which are the larger diameter of the grinding wheel and regulating wheel respectively, are opposite to one another and thus form the smaller end of the grinding throat. Attention is also invited to the fact that the surface of the work rest blade is also inclined'longitudinally so that the blade has a high end and'a low end, the high end being adjacent or between the rims 51a and 56a while the low end is opposite the rim 50a of the grinding wheel at the entrance of the throat.

The angles of inclination of. each peripheral face of the wheels and of the top surface of the blade are all made the same and equal to the angle of taper to be ground on the workpiece. Thus, the axis C of the grinding throat may be horizontal, so as to support theaxis of the work in a horizontal plane, but the supporting elements of the conical grinding throat, that is the supporting lines of contact of the two wheels and the blade with the work, all converge at the same angle to the horizontal axis of the throat.

The face of the grinding wheel is wider than the length of the work, whereby the unground workpiece may be dropped into the wider end of the throat, onto the blade as shown in Fig. .4 and then moved along the blade for grinding to the position shown in Fig. 5. Since the throat gets narrower as the work progresses, it will be obvious that stock'will be removed from the work by grinding; and the further the work moves, the more stock will be removed, thus reducing the size of the workpiece.

Since it is desirable to grind the work to some definite size, it is obvious that the movement of the work must be stopped at some definite point in its progress, otherwise the work would be ground too small. Attention is also invited to the fact that since the work rest blade is inclined, the work moves uphill and not strictly axially whereby there is a gravitational component tending to cause the work to slide downhill. Also, since the work is moving into a narrowing Wedge between the peripheral faces of the wheels, there is a retrograde reaction tending to oppose the advance ofthe work; Thus, the grinding throat is of such a nature that it sets up a force reaction on the'work opposing its advance into the grinding throat.

In this machine, a solid metallic regulating wheel is preferably utilized because it wears longer, and also because it is easier to cut work ejector notches in it, which will subsequently be described.

It should also be noted that the regulating wheel may be made cylindrical or circular, whereas it is the usual practice to make notched regulating wheels eccentric so as to produce the equivalent of an infeeding action on the work to reduce its diameter. Since an eccentric surface on a regulating wheel is diflicult to produce and to maintain its accuracy, it will be seen that a notched circular regulating wheel is easy to produce and to maintain the work engaging surface thereon. Since the peripheral face of the regulating wheel is circular, in cross section this face does not impart any infeeding component to the work or effect any reduction in work size.

Actual work reduction or grinding is effected by cam means attached to one side face of the regulating wheel and positioned to engage the end of the work and push it endwise through the grinding throat in abrading contact with the grinding wheel. It will thus be seen that although the wheels are circular in cross section and the regulating wheel does not have a surface to produce feed component on the Work, the conditions are the same as in infeed grinding. However, the work is moved as in through feed grinding, and the wheels remain stationary, that is, remain a fixed distance apart, and their axes are parallel.

The regulating wheel is illustrated as provided with two work ejector notches, but the same principles apply whether the notches are more or less than two. For each work ejector notch, there is a work feeding cam, and since two notches are shown, there are two work feeding cam mechanisms.

Two cams 66, having arcuate conformations, are connected by bolts 67 to the outer recessed margin 55c of the side face 55 of regulating wheel 30. Each cam 66 extends circumferentially around a portion of the regulating wheel but less than 180 degrees. The cams are therefore spaced from each other at each end and define two portions 68 of the regulating Wheel between the respective ends of the cams. Each cam has a forward end 66a and a rear end 66b, in relation to the direction of rotation of the cam as it is rotated about the axis B of the regulating wheel 30 by that'wheeL. Each cam 66 extends beyond the periphery 55a of the side face 55 of the regulating wheel and has a cam surface indicated generally the throat. As each cam rotates past the position of the blade 61, the cam surface 69 faces, and is in registration with, a workpiece 65 resting on the blade 61 within the throat. The cam surface 69, as shown in Fig. 3, consists of three portions: a forward dwell portion 69a where the cam surface is parallel to the side face of the regulating wheel, a central feed portion 6% where the cam surface is inclined, and a rear dwell portion 69c where the cam surface is again parallel to the side face of the regulating wheel. The relative position of the cam surfaces 69a, 69b, and 690 are such that as the regulating wheel rotates to carry the cam past the position of the blade 61, the portion 69a of the cam surface is first in registration with a workpiece on the blade. As the cam continues to rotate the portion 69b and then the portion 69c come into registration with the workpiece.

Two notches '75 are cut in the rim of the regulating wheel, one at the rear of each cam 66. Each notch has a front wall 75a sloping from immediately behind the rear of the cam, a beveled bottom wall 75b tapering toward the side face 55 of the regulating wheel 30, and a beveled rear wall 750, also tapering toward the front face 55 of the regulating wheel 36 to define a notch with a generally tapered conformation.

As indicated by the arrows, E and F, in Fig. 2 each of the wheels and 34) rotate in a clockwise direction around their respective central axes A and B. The grinding wheel rotates at a relatively high angular velocity for cutting and the regulating wheel 31) at a relatively slower angular velocity to regulate the rotation of the workpiece 65 and hence the relative motion of its surface and the cutting surface 52 of the grinding wheel.

The workpieces 65 may be inserted into the throat 6% between the wheels 15 and 30 by a conventional loading device such as one similar to that shown in US. Patent 1,851,265, issued to Strickland and Zimmerman, or US. Patent 1,932,952, issued to Binns.

In the grinding operation, the workpiece 65 is deposited on the blade 61 in the throat 60 towards the large end diia of the throat when the portion 68 of the regulating wheel 39 is passing the blade position. The workpiece 65 seats on the blade 61, and, as the regulating wheel 39 and cam 66 rotate, the forward portion 66a of the cam advances to a position adjacent the blade, and the cam surface 69a comes into registration with the larger end 65a of the tapered workpiece. Since the cam surface 6% is parallel to the face 55 of the regulating wheel 38, no feeding action occurs. The position of the workpiece at this time is shown in Fig. 4. As the regulating wheel 38 continues to rotate the cam surface 6% comes into registration with the larger end 65a of the workpiece 65, and, since that surface of the cam is inclined gradually, the workpiece is urged along the blade 61 toward the narrow end 6% of the throat. During this time, the workpiece 65 is rotated about its central axis D between the cutting face 52 of the grinding wheel and the work positioning face 57 of the regulating wheel 30. The faces move in opposite directions at the points where they contact the workpiece 65 and the action of the regulating wheel on the workpiece causes relative rotation between the workpiece and the cutting face 52 of the grinding wheel for removal of material from the workpiece. At the end of the contact between the cam surface 6% and the workpiece 65 the workpiece has been urged to a predetermined position, as shown in Fig. 5, which defines the final size of the part. At that time the cam surface 690, which is parallel to the face 55 of the regulating wheel 30, rotates into registration with the end 65a of the workpiece and, consequently, feeding thereof is stopped. During the time the cam surface 690 rotates past the blade position it holds the workpiece at the predetermined position for sparking out of the work and producing the finished surface thereon.

As the regulating wheel continues to rotate, the notch 75, which is immediately behind cam 66 in relation to the direction of rotation of the regulating wheel 39, passes the blade position and the workpiece 65, which is resting on the surface 62 sloping toward the regulating wheel 30, drops into the notch as shown in Fig. 6. Due to the sloping wall 75b, the workpiece 65 is ejected from the notch 75 and therefore the notch acts as a work ejecting means. A second piece is loaded while portion 68 passes the blade position and the grinding operation described above is performed on that piece. It will be noted that in the specific embodiment shown, where two cams 66 and two notches 75 are on the regulating wheel 39, two workpieces may be completed with one revolution of the regulating wheel. With only one cam and one notch on the regulating wheel, one workpiece would be completed per revolution, or, with more than two cams a corresponding number of pieces would be made in one revolution.

It will be noted that the cam means are fixed for rotation with the regulating wheel, and therefore as the regulating wheel rotates to time the rotation of the work, the cam means rotating with it, times the feeding action of the work, so that the feeding action is completed during rotation of the regulating wheel through a predetermined are or angle of rotation.

It will thus be seen that a new and improved centerless grinding mechanism has been provided for grinding short tapered workpieces.

What is claimed is:

1. In a centerless grinding machine, a rotatable grinding wheel having a peripheral cutting surface of circular cross section, a rotatable regulating wheel of circular cross section opposite said grinding Wheel having a peripheral workpiece engaging surface, said wheels mounted on parallel centered axes positioned a fixed distance apart and said surfaces equally beveled to define a constant sized tapered grinding throat therebetween, a blade between the wheels inclined in the longitudinal direction to support a tapered workpiece in the throat with its axis parallel to the axis of the Wheels, a cam connected to the regulating wheel on the side face at the wide end of the tapered grinding throat, said cam having a circumferentially extending arcuate cam surface extending radially beyond the workpiece engaging surface of the regulating wheel and facing the throat, said cam surface inclined a predetermined amount to engage a workpiece on the blade and feed said workpiece endwise in the throat toward the narrower end thereof in abrading contact with the grinding wheel to a predetermined position therein for grinding said workpiece to a predetermined size, and a notch in the periphery of the regulating wheel behind the cam surface in relation to the direction of rotation of the regulating wheel for release of the workpiece from the grinding throat.

2. In a centerless grinding machine, a rotatable grinding wheel having a peripheral cutting surface of circular cross section, a rotatable regulating wheel of circular cross section opposite said grinding Wheel having a peripheral work piece engaging surface, said wheels mounted on parallel centered axes positioned a fixed distance apart and said surfaces equally beveled to define a constant sized tapered grinding throat therebetween, a blade between the wheels inclined in the longitudinal direction to support a tapered workpiece in the throat with its axis parallel to the axis of the wheels, a cam rotatable with the regulating wheel, said cam having a circumferentially extending arcuate cam surface extending radially beyond the workpiece engaging surface of the regulating wheel and facing the throat, said cam surface inclined a predetermined amount to engage a workpiece on the blade and feed said workpiece endwise in the throat toward the narrower end thereof in abrading contact with the grinding Wheel to a predetermined position therein for grinding said workpiece to a predetermined size, and a notch in the periphery of the regulating wheel behind the cam surface in relation to the direction of rotation of the regulating wheel for release of the workpiece from the grinding throat.

-" 731 In' a' centerless grinding machine, a rotatable grinding wheel having a peripheral cutting surfaceof circular cross section, a rotatable regulating wheel of circular cross section opposite said grinding wheel having a peripheral workpiece engaging surface, said wheels mounted on centeredaxes lying'in a common plane a fixed distance apart with said surfacespositioned to define a constant sized tapered grinding throat'therebetween, a blade between the wheels inclined in the longitudinal direction to support a workpiece in the throat, a cam rotatable with the regulating wheel, said cam having a circumferentially extending arcuate cam surface extending radially beyond the workpiece engaging surface of the regulating Wheel 7 and facing the throat, said cam surface inclined a predetermined famount to engage a workpiece on the blade and feed said workpiece endwise in the throat toward the narrower end thereof in abrading contact with the grinding wheel to a predetermined position therein for grinding said workpiece'to a predetermined size, and a notch in the periphery of the regulating wheel behind the cam surface in relation to the direction of'rotation of the regulating wheel for release of the workpiece from the' grinding throat.

4. In a centerless grinding machine, a rotatable grindt 8 ing wheel having a peripheral cutting surface of circular cross section, a rotatable regulating wheel of circular cross section opposite said grinding wheel having a pe- 'ripheral workpiece engaging surface, said wheels mounted on centered axeslying substantially ina common plane a fixed distance apart with said surfaces positioned to define a constant sized tapered grinding throat therebetween, a blade between the wheels inclined in the longitudinal direction to support a workpiece in the threat, a cam rotatable in timed relation to the rotation of the regulating wheel and operable at least once each rotation of the regulating wheel to effect endwise movement of a workpiece on the'blade toward the narrower end of the throat in abrading contact With the grinding-wheel to a predetermined position in the throat for grinding said workpiece to a predetermined size, and means operable intimed relation to the rotation of the regulating wheel to releasea workpiece in said predetermined position from the throat,

References Cited in the file of this patent UNITED STATES PATENTS 

